The aerodynamic inefficiencies associated with the traditional configuration of a pickup truck are well known. These inefficiencies are due, in large part, to the bluff-body passenger cab and the open bed of the truck closed off by a tailgate. Ambient airstreams flow relatively smoothly over the truck cab. However, when the airstream flows down into the rear bed portion of the truck, three phenomena develop during this transition which affect the base drag and aerodynamic lift forces: flow separation (also known as “eddy shedding”), turbulent airflow, and aerodynamically unfavorable pressure gradients. These phenomena can lead to, among other things, reduced fuel efficiency and vehicle instability. Notably, at typical highway cruising speeds, the majority of fuel consumed by an automobile is spent in overcoming aerodynamic drag-aerodynamic drag increasing with the square of speed.
Efforts have been made to remedy or at least alleviate the aerodynamic inefficiencies associated with the standard configuration of a pickup truck. It is well known in the prior art to attach a wing or spoiler, similar in geometry to an airfoil, to the vehicle in order to modify airflow around the vehicle in order to provide certain predetermined aerodynamic responses during vehicle operation. Another proposed remedy is to reconfigure the truck bed by including a camper shell or a bed cover, also known as a tonneau cover. The covers can be hard or soft, elevated or flush-fit.
Although these approaches do help to reduce aerodynamic drag, the benefits provided are minimal. Additionally, bed covers and camper shells provide little or no reduction in aerodynamic lift forces. Finally, permanently mounting a spoiler, camper shell, or bed cover to the pickup truck may reduce the functionality and convenience provided by the pickup bed and tailgate, intended for use in heavy loading and unloading.
As federal standards for fuel economy become more stringent and fuel costs increase, improved aerodynamic drag on pickup trucks may be required. Accordingly, it is desirable to provide a device that is capable of significantly reducing the aerodynamic drag on standard pickup trucks without reducing the normal functionality of the tailgate. Finally, the device should limit the amount of lift force and yawing moment inflicted upon the bed portion of the pickup truck.